1. Field of the Invention
The present invention relates to a phase shifter using a substrate integrated waveguide (SIW), and more particularly, to a phase shifter implemented through the formation of air holes and dielectric insertion in an SIW.
2. Description of the Related Art
A phase shifter is a device that changes or adjusts the phase of an electrical signal. It is widely used in microwave system applications such as wireless communication, radar, and measurement equipment. Phase shifters can be implemented in various ways. In particular, phase shifters using a substrate integrated waveguide (SIW) have recently been developed.
An SIW includes columns of via walls, which are arranged parallel to each other, on a dielectric substrate. Thus, it has a similar function to a conventional waveguide. In addition, the SIW has the advantages of both the conventional waveguide and a microstrip transmission line, like high Q factor, high power capacity, smaller size, and the possibility of integration. These advantages enable the SIW to be widely used in microwave and millimeter-wave circuits such as resonators, filters, and antennas. Phase shifter recently developed using this SIW are implemented by inserting ferrite toroid into the SIW or inserting a metal pole into the middle of the SIW.
Phase shifters must be designed to meet various performance requirements in terms of insertion loss, bandwidth, power capacity, size, weight, phase error, and the like. However, phase shifters using ferrite toroid are difficult to manufacture and are large in size and weight. On the other hand, phase shifters having a metal pole inserted into the middle of an SIW can easily adjust an amount of phase change by changing the position of the metal pole. However, since insertion loss increases as the amount of phase change increases, there is a limit to the amount of phase change.